It has been demanded for long an instrument which permits measurement inside a living body easily without harming the living body in fields such as clinical medicine and brain science. For such demand, an instrument, which measures inside a living body by irradiating light having wavelength from visible to infrared onto the living body and thereafter by detecting the light passed through the living body, is, for example, disclosed in JP-A-9-98972 (hereinbelow will be referred to as document 1) and JP-A-9-149903 (hereinbelow will be referred to as document 2).
The “biological optical measurement instrument” disclosed in these documents was constituted by a modulation use semiconductor laser which generates light beams having different modulation frequencies, irradiation use optical fibers which introduce the generated light beams to a living body and irradiate the same at different positions thereof, detection use optical fibers which collect light beams passed through the living body and introduce the same to photo diodes, a measurement probe which secures the top end portions of the irradiation use and detection use optical fibers at predetermined positions on the living body, a lock-in amplifier which separates wavelength and reflection light intensity corresponding to the irradiation positions from electrical signals representing light intensity passed through the living body and outputted from the photo diodes (hereinbelow will be referred to as “living body passed light intensity signal”), an A/D converter which converts outputs of the lock-in amplifier to digital signals, and a display unit which computes relative variation amounts of oxy- and deoxy-hemoglobin concentrations at every measurement points from the living body passed light intensity signals after the A/D conversion and displays the computed relative variation amounts as a living body passed light intensity picture image (a topography picture image).
The conventional measurement probe was constituted by an optical fiber fixing member which arranges the top ends of the irradiation use optical fibers and the detection use optical fibers alternatively in a grid shape and a fixing belt which fixes the optical fiber fixing member to the living body. The optical fiber fixing member was formed, for example, from a base member of a plastic sheet having thickness of about 3 mm into a helmet or cap shape. To the optical fiber fixing member a belt was attached and through which the optical fiber fixing member was fixed to the living body.
The optical fiber fixing member is provided with a plurality of holes corresponding to a plurality of positions where the light beams are irradiated to the living body and detected therefrom and optical fiber holders were arranged in each of the holes. The optical fiber holder is constituted by a hollow shaped holder main body, a nut screw and an optical fiber fixing screw, and with the nut screw the holder main body is fixedly attached to the optical fiber fixing member. Inside the holder main body the irradiation use optical fiber or the detection use optical fiber was inserted and then fixed with the optical fiber fixing screw while softly contacting the optical fiber onto the surface of the living body.
As the result of investigation of the above referred to conventional art, the present inventors found out the following problems.
In association with the progress of the recent medical technology, many portions of a patient can be cured by an early detection, and, in particular, an inspection device which is suitable for an early detection of encephalopathy of a newborn or for monitoring cerebral thrombus during cardiac operation is keenly demanded.
For example, it has been recognized that in a case of speech impediment of a newborn caused by encephalopathy, since the portion relating to language function of a newborn has been established at an early stage, therefore, if a proper treatment has not been carried out by detecting encephalopathy before the language function establishment the newborn can not speak language in his or her entire life time. For this reason, an inspection device which permits an early detection of encephalopathy of a newborn is strongly demanded.
Further, in a case of a newborn who has born with visual disability, it is impossible to recognize the visual disability by the newborn him or herself and generally such as the parents detect the visual disability. However, it is frequently required time of about one year after the birth until the parents note the visual disability of the newborn which causes a problem with regard to early detection and early treatment.
As an inspection device which resolves the above problem, a biological optical measurement instrument, which unnecessitates fixing of a measurement portion during measurement, shows a low restraint property and permits measurement in any places and any environment, has drawn attention.
However, a conventional biological optical measurement instrument was developed under a precondition that a subject is in sitting or standing-up position, therefore, in a case of a living body such as a newborn who is difficult to be kept in sitting or standing-up position, there arises a problem which prevents correct measurement, because the contact positions between the scalp and the irradiation use and detection use optical fibers displace, when the head moves.
Likely, even during monitoring of cerebral thrombus which is caused by clogging a blood vessel in the brain with a thrombus caused during cardiac operation and being carried into the brain, since the body position of a living body is in a lateral decubitus, there also arises a problem which prevents measurement, because the contact positions between scalp and the irradiation use and detection use optical fiber displace.
Further, in a case of a living body such as a newborn whose hair is comparatively thin, it is possible to contact the irradiation use and detection use optical fibers to the scalp while comparatively easily avoiding hair, however, in a case of a living body such as an adult who has a plenty of hair and each of which is hard, there was a problem that it is difficult to avoid hair.
An object of the present invention is to provide a biological optical measurement instrument which permits biological optical measurement of a living body in lateral decubitus.
Another object of the present invention is to provide a biological measurement instrument which permits to avoid hair easily at the time when attaching a measurement probe to a living body.
Still another object of the present invention is to provide a biological optical measurement instrument which permits biological optical measurement while providing a predetermined stimulation to a subject.
A further object of the present invention is to provide a biological optical measurement instrument which permits to enhance diagnosis efficiency in the course of biological optical measurement.
The above and other objects and novel features of the present invention will become apparent from the description in the present specification and the attached drawings.